A power semiconductor circuit is provided for clamping the voltage across the circuit when a power semiconductor switch is opened (i.e., turned off). The circuit may include a first surge arrester and a first semiconductor switch coupled in parallel with the power semiconductor switch. The first semiconductor switch is coupled in series with the first surge arrester. A second surge arrester may be coupled to the gate of the first semiconductor switch to control current flow through the first semiconductor switch and the first surge arrester.

A circuit protection apparatus includes separable contacts, an operating mechanism, an electronic trip unit storing a plurality of trip parameter combinations, wherein each of the trip parameter combinations specifies a certain value for each of a plurality of individual trip parameters, and a multi-position selector moveable among a plurality of predetermined positions and configured to enable selection of one of the predetermined positions. Each of the positions corresponds to a respective one of the trip parameter combinations, wherein the electronic trip unit is structured to, responsive to a chosen one of the plurality of predetermined positions being selected by the multi-position selector, cause the one of the trip parameter combinations corresponding to the chosen one of the plurality of predetermined positions to be used by the electronic trip unit to determine whether to cause the operating mechanism to trip open the separable contacts.

A circuit breaker includes a set of separable contacts moveable between a closed position and an open position, an operating mechanism configured to open the set of contacts, a conductor coupled to the set of contacts, a current transformer coupled to the conductor, and a trip circuit coupled to the operating mechanism and to the current transformer and configured to cause the operating mechanism to open the set of contacts when a current through the conductor exceeds a current threshold that is greater than a saturation threshold of the current transformer. The trip circuit is further configured to vary the current threshold during an interval following a closure of the set of the contacts and to provide a fixed current threshold thereafter.

A trip apparatus for a circuit interruption device that comprises a coil operatively connectable to a circuit interruption device. The coil is configured to selectively operate the circuit interruption device to interrupt when a current flowing through the circuit interruption device exceeds a threshold. The trip apparatus also includes a current measuring device configured to selectively measure a coil current flowing through the coil to determine a measured coil current signal. In addition, the trip apparatus includes a monitoring device configured to determine the derivative of the measured coil current signal and to perform a correlation of the derivative of the measured coil current signal and a reference derivative of a reference coil current signal to determine a correlation output. The monitoring device is further configured to compare the correlation output with a reference correlation threshold to determine whether an operating condition of the coil is normal or abnormal.

A circuit breaker having, in a current path, a switching device having a thermal and/or magnetic tripping device for interruption of a current circuit having the current path comprehensive in an event of overcurrent or short-circuit, wherein a functional component of the switching device connected into the current path is bridged by means of a bypass which carries the load current detected by means of a current sensor when the current is below a current threshold, and is shut off when the current threshold is exceeded.

The application relates to a power switch for breaking an electrical circuit when current and/or current time span threshold values are exceeded, including an energy converter, which on the primary side is connected to the electrical circuit, and on the secondary side provides an energy supply for at least one control unit of the power switch. A choke is connected between the secondary-side output of the energy converter and the control unit of the power switch.

A circuit interruption device (e.g., a molded case circuit breaker) includes at least one set of contacts, a contact actuator mechanism configured to open the at least one set of contacts and a trip control circuit configured to cause the contact actuator mechanism to open the at least one set of contacts responsive to a condition satisfying a first trip criterion and to apply a second trip criterion (e.g., a lower current level trip threshold) responsive to the opening of the at least one set of contacts. The trip control circuit may be configured to apply the second trip criterion after a succeeding closure of the at least one set of contacts. The trip control circuit may be further configured to return to application of the first trip criterion after lapse of a predetermined interval following the succeeding closure of the at least one set of contacts.

A control circuit for an electric leakage circuit breaker, capable of preventing an error in determining an electric leakage generation due to an offset voltage of an input amplifier, including, a zero phase current transformer configured to detect a zero phase current on a circuit as a leakage detection signal, a filter circuit section configured to remove a high frequency noise included in the leakage detection signal, an input amplifier configured to a voltage formed by a current of the leakage detection signal and an impedance of the filter circuit section, and includes a pair of transistors, a base current generator commonly connected to the bases of the pair of transistors and configured to supply the same amount of base current to the pair of transistors, and a trip determination circuit section configured to determine whether to output a trip control signal.

A protective device including: a plurality of line terminals and a plurality of load terminals a circuit interrupter including a solenoid and a set of interrupting contacts that connect at least one line terminal and at least one load terminal in a reset state and disconnect the at least one line terminal and the at least one load terminal in a tripped state; a voltage detection element configured to detect voltage across the plurality of line terminals and generate a line voltage rejection signal when greater than a predetermined overvoltage; a reset assembly including a reset button and a reset switch operatively coupled to the reset button; and a reset prevention mechanism configured to prevent the circuit interrupter from entering the reset state when the reset signal is absent.

A contact monitoring unit is for a safety-critical triggering apparatus of a switching device, including a connection diagram arranged on a first circuit carrier medium for a triggering apparatus and triggering electronics arranged on a second circuit carrier medium. The contact monitoring unit includes redundant electrical connections that are monitored such that, even a failure of a redundant electrical connection is detected.